help---what is the answer to this question

Virgil

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If you’re in outer space traveling in a spaceship at the speed of light, and theoretically, if you could stick a gun out the window and fire a bullet that travels at 265 feet per second, how long would it take the spaceship to pass the bullet?


I said the bullet would never leave the barrel. what is the right answer.



Virgil
 
Let's get the question right first. Since you CANNOT travel at the speed of light, this question makes no sense. It is not possible for anything with mass to reach the speed of light so asking what would happen if one could is a meaningless question.

If you're travelling close but not at the speed of light then the bullet leaves the barrel (relative to the person pulling the trigger) at 625 feet per second.
 
This is a question that has too many variables for me to answer. Even at .9999999 the speed of light the bullet is not going to excede the speed of light, if you fire it along the axis of motion in the direction of travel, the bullet will be constrained to not travel faster than the speed of light. If you fire in any other direction the bullet will be constrained so that it's velocity will not excede the speed of light but it may appear that the bullet is traveling at it's 'normal' velocity.
 
Hamish has it right. I assume you mean you (A) are traveling near the speed of light at a constant velocity relative to some observer (B). "A" could say he is standing still and B has a velocity near the speed of light in the opposite direction (both reference frames are equivalent). So for A, the velocity of the bullet is 265 feet per second, no matter which way she points the gun.

"B" will see things differently...
 
No matter how hard I try, I just can't grasp how something could go at 300 feet per second for person A (In the direction he is travelling, at 99.whatever% the speed of light), while person B sees them both going the same speed.

I mean, doesn't the bullet seem farther away from person A? But B sees it closer? I don't understand...
 
sorgoth said:
No matter how hard I try, I just can't grasp how something could go at 300 feet per second for person A (In the direction he is travelling, at 99.whatever% the speed of light), while person B sees them both going the same speed.
Click to expand...

B doesn't see them both going the same speed. What gave you that impression?
 
Virgil said:
If you’re in outer space traveling in a spaceship at the speed of light, and theoretically, if you could stick a gun out the window and fire a bullet that travels at 265 feet per second, how long would it take the spaceship to pass the bullet?


I said the bullet would never leave the barrel. what is the right answer.



Virgil
Click to expand...

Please review the excellent response given by Hamish. Since no object with mass can travel at the speed of light, your question has no premise.

Further, assuming that the space ship was going at something less that the speed of light, then one would need to know how long is the space ship, and which way the gun is pointed in order to properly answer your question.
 
Let's say you're able to fire the gun from the front end of the spaceship. The spaceship would be slowed by the recoil of the gun; the spaceship would never pass the bullet.
 
Virgil said:
If you’re in outer space traveling in a spaceship at the speed of light, and theoretically, if you could stick a gun out the window and fire a bullet...
Click to expand...


I always wondered how they could transport people on and off the Enterprise while it was at "warp", but I never thought about Riker shooting a gun out the window...;)
 
Re: Re: help---what is the answer to this question

zenith-nadir said:
I always wondered how they could transport people on and off the Enterprise while it was at "warp", but I never thought about Riker shooting a gun out the window...;)
Click to expand...
A more fundamental observation, I always wondered why the Enterprise made a "whoosh" anytime it flew by the camera...
 
Re: Re: Re: help---what is the answer to this question

Yahweh said:
A more fundamental observation, I always wondered why the Enterprise made a "whoosh" anytime it flew by the camera...
Click to expand...


A subsystem of the warp coil is the "whoosh generator"...don't you know anything Yahweh? ;)
 
Hamish said:
If you're travelling close but not at the speed of light then the bullet leaves the barrel (relative to the person pulling the trigger) at 625 feet per second.
Click to expand...

Was that a typo, or something else I have no hope of understanding?
 
I wondered myself. I'm assuming it's some kind of relativistic effect caused by typing too fast.
 
That was indeed a typo. :o

My point was supposed to be that the person in the spacecraft who fires the gun would experience the bullet leaving the gun at exactly the same velocity as if the spacecraft were "not moving". The motion of the bullet relative to the spacecraft is always 265 (and no other permutation of those numbers) feet per second as seen by the person firing the gun.
 
I think we are all missing the obvious here.

The velocity of the spaceship is irrelevant. Let's call it 265 ft/sec.

Fire the gun (pointing in the same direction as the ship is headed).

When will the ship pass the bullet?

Assuming we are in a frictionless vacuum, it never will.
The ship is not accelerating. How can it catch the bullet?

In Virgil's example, if the ship is infinitely close to c, the bullet still leaves the gun at 265 ft/sec relative to the gun, just as it would if the pilot stuck it in his ear and pulled the trigger. The total forward V of the bullet will still be less than c , measured in the same reference system as the ship. The total length of the ship (and of the ship/ bullet system ) will be reduced by L-F contraction, but I don't see what difference the length makes...?
 
sorgoth said:
No matter how hard I try, I just can't grasp how something could go at 300 feet per second for person A (In the direction he is travelling, at 99.whatever% the speed of light), while person B sees them both going the same speed.

I mean, doesn't the bullet seem farther away from person A? But B sees it closer? I don't understand...
Click to expand...
Time and space do weird things as two things travel at near the speed of light relative to each other.

Person B doesn't see the bullet travel at the same speed as person A; he sees it going just the tiniest bit faster. But you're right about the distance... sort of. Person A would logically see the bullet further away from the spaceship than person B does at the same time.

So what gives? Time. Time gives. Time is slowed down for person A (and the bullet and the spaceship) relative to person B. And distance gives. If the spaceship were 100 yards long and flew past a 100-yard-long stationary (to person B) measuring device, person B would see the ship being shorter than 100 yards. Not only that, the front of the ship would look as if it were rotated away from person B.

The moral of the story is: You can't go faster than the speed of light. If you try to, then time, space, and mass will triple-team you and change their own definitions so that you can't. Highly unsporting of them, but true.
 
Well, I don't know that you cant go faster. You just can't go at c. (And of course getting anything massive much over 0.95c will take the entire energy output of a healthy star).
But you can shoot a gun out the window .
 
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